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|  MIL-E-23457B(SHIPS)
required. Filters shall be constructed of brass, bronze, or other metals which are not
readily corroded by sea water contaminated fuels. Coated steel or untreated aluminum are
not acceptable. Filters shall include vents to permit the expulsion of air. Manually
operated drain valves shall be provided to completely drain filter bodies without the use
of tools.
3.8.3.3.1 Primary filter. Primary filters (strainers) shall be the simplex metal
#
edge type with 0.003 to 0.0035 inch spacing, enclosed manually operated cleaning device and
sediment drain. The term "metal edge" is defined as stacked metal discs or helically
wound flat metal wire or metal ribbon media. Wire cloth, screen sintered metal, or
perforated plate media are not acceptable for simplex strainers.
3.8.3.3.2 Duplex secondary filters. Duplex filters shall consist of two filter units
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connected to the common head or placed together equipped with a three-way plug valve, disposable
filter elements, and mounting arrangement. The lever operated valve shall direct flow
through one side to permit element change and cleaning of the other side without interruption
of flow. Each side shall be sized to accommodate twice the full flow of fuel supplied to
the engine fuel manifold supply line or supply header at rated load of the engine and
employ drain valves to permit complete draining. Filter elements and materials used for
metal parts and gaskets shall be in accordance with MIL-F-20627. Filter elements shall be
rated at 150 gallons per hour (gal/hr) in lieu of the 50 gal/hr stated in MIL-F-20627.
3.8.3.4 Fuel oil priming pump. A hand operated fuel oil pump shall be furnished with
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the capacity to prime the engine fuel oil system within 2 minutes at an ambient temperature
of 70F.
3.8.3.5 Fuel consumption. 4.1 When engines are subjected to the first article inspection
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(see 4.4), fuel consumption shall be measured and recorded (see 4.4.2.3).
3.8.3.6 Fuel inlet temperature. The fuel temperature at the engine supply pump inlet
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shall not exceed 115F. The installing activity, by the use of coolers or other means, shall
insure that this requirement is met. Coolers, if used, shall be sea water cooled and shall
be in accordance with 3.8.2.2.
3.8.4 Lubricating system. Lubricating oil shall conform to MIL-L-9000 for ambient
#
condition above 20F. The same grade of lube oil shall be used in the engine and attached
accessories. Engines shall be provided with an oil level indicator, filling opening, and
accessible sump drain connection or a sump pump to drain or clean the engine oil pan.
Bayonet type oil level indicators shall be shielded to permit accurate readings while the
engine is running. The lubricating oil system shall be arranged as shown on figure 1.
Engines shall be provided with suction and pressure connections for priming and flushing the
engine lubrication system.
#
3.8.4.1 Lubricating oil pumps. Pressure pumps, scavenging pumps, and piston cooling
oils pumps shall be of the positive displacement type, driven by the engine. The scavenging
pump, if required, capacity shall be approximately 1-1/4 times the capacity of the pressure
pump and shall have an oil flow capable of scavenging the system from idle to rated-speed.
A relief valve shall be provided for the outlet of each pump. If the pump suction incor-
porates a check valve, means shall be provided to prevent excessive build-up in the suction
line in case the engine and pump are rotated backwards.
#
3.8.4.2 Coolers. Lubricating oil coolers shall be fresh water cooled and shall be in
accordance with 3.8.2.2 The use of cooler cores installed in an enclosed area integral
to the engine is permitted provided the core construction and materials meet the require-
ments of 3.8.2.2.
#
3.8.4.3 Lubricating oil filters. Engines shall use full-flow filter elements con-
forming to type IV of Full-flow filter relief valves shall be external
of the filter case. Valves shall bypass oil when the pressure gage drop is between 20 and
2
25 lb/in2. The valve closing gage pressure shall be not less than 20 lb/in . The filter
inlet shall be internally baffled or so constructed to prevent the oil flow from impinging
directly on the filter elements. The filter shall include a hand operated drain valve
which shall completely drain the filter for servicing. The filter shall be the simplex
type.
3.8.4.4 Lubricating oil strainers. Strainers shall be either the simplex metal edge
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type or the duplex metal edge or basket type. The strainer shall be sized to carry the
full-flow of 150 standard saybolt universal (sSU) viscosity oil with a pressure gage drop
of not more than 5 lb/in2 with clean elements. The strainer bypass valve shall be set to
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